The uniqueness isn't just that they are using lasers (that's been done) but that they are using only lasers. There are many different ways you can get pair prod

The uniqueness isn't just that they are using lasers (that's been done) but that they are using only lasers. There are many different ways you can get pair production from high energy photons, one of the easiest is via an interaction with a charged massive particle (such as an electron, proton, or atomic nucleus). But it's also possible for pair production to be a purely photon only process (just as the reverse process of annihilation producing only photons is possible), however that is a lot more difficult to pull off experimentally.